Effect of static electric fields on liquid water, its structure, dynamics, and hydrogen bond asymmetry: A molecular dynamics simulation study of TIP4P/2005 water model.

Abstract

We study the effect of static electric fields of 0.1, 0.4, and 1.0 V/nm on the hydrogen bond structure and dynamics of TIP4P/2005 water at 1bar and at temperatures between 300 and 200K using molecular dynamics simulations. At all these temperatures, simulating liquid water with electric fields of 0.1 and 0.4 V/nm has no additional effect on its structural and dynamical changes, which otherwise already take place due to cooling. However, the introduction of 1.0 V/nm field enhances the slowing down of liquid water dynamics, crystallizes it to cubic ice at 240 and 220K, and amorphizes it at 200K. At 240 and 220K, crystallization occurs within 5 and 50ns, respectively. An electric field of 1 V/nm increases the relaxation times in addition to what cooling does. We note that when liquid water's metastability limit is reached, crystallization is averted and amorphization takes place. Both equilibrium (liquid-solid) and non-equilibrium (liquid-amorphous) transformations are observed at 1 V/nm. Moreover, with an increase in the electric field, H-bonds become stronger. However, the donor-acceptor asymmetry (the difference between the strengths of two donor/acceptor bonds) remains even when crystallization or amorphization takes place. At low temperatures, increasing electric fields on liquid water increases both its crystallization and amorphization tendencies.